Publications

Water photoelectrolysis cells based on photoelectrochemical water splitting seem to be an interesting alternative to other traditional green hydrogen generation processes (e.g. water electrolysis). Unfortunately the practical application of this technology is currently hindered by several difficulties: low solar-to-hydrogen (STH) efficiency expensive electrode materials etc. A novel concept based on a tandem photoelectrolysis cell configuration with an anion-conducting membrane separating the photoanode from the photocathode has already been proposed in the literature. This approach allows the use of low-cost metal oxide electrodes and nickel-based co-catalysts. In this paper we conducted a study to evaluate the economic and environmental sustainability of this technology using the environmental life cycle cost. Preliminary results have revealed two main interesting aspects: the negligible percentage of externalities in the total cost.

To address the collaborative optimization challenge in multi-microgrid systems with significant renewable energy integration this study presents a dual-layer optimization model incorporating power-hydrogen coupling. Firstly a hydrogen energy system coupling framework including photovoltaics storage batteries and electrolysis hydrogen production/fuel cells was constructed at the architecture level to realize the flexible conversion of multiple energy forms. From a modeling perspective the upper-layer optimization aims to minimize lifecycle costs by determining the optimal sizing of distributed PV systems battery storage hydrogen tanks fuel cells and electrolyzers within the microgrid. At the lower level a distributed optimization framework facilitates energy sharing (both electrical and hydrogen-based) across microgrids. This operational layer maximizes yearly system revenue while considering all energy transactions—both inter-microgrid and grid-to-microgrid exchanges. The resulting operational boundaries feed into the upper-layer capacity optimization with the optimal equipment configuration emerging from the iterative convergence of both layers. Finally the actual microgrid in a certain area is taken as an example to verify the effectiveness of the proposed method.

Hydrogen production from gasification of biowaste generates large volumes of CO2 due to endothermic biowaste decomposition. Alternatively the Sun can provide that energy. To evaluate the yield and performance of solarbased gasifiers at country scale a multi-scale approach is required. First the operation of a solar gasifier is analyzed by developing a two-phase model validated and scaled to industrial level. Next the performance and yield of such technology as a function of the radiation received is studied taking Spain as a case study. The results were promising obtaining a syngas rich in H2. However tar and char were not reduced due to insufficient temperature. Scale-up studies revealed energy losses to the environment in the industrial-scale gasifier which suggested the use of segmented heating. In turn diameters no larger than 0.8 m and biomass feeding rates below 0.85 kg/s highlight the deployment of a modular design due to particle size limitations. Finally the large-scale waste valorization showed that the gasifier can only operate in Spain in the summer months. It can run over 180 h/month and more than 250 days/year only in C´ adiz and Santa Cruz de Tenerife which also showed the highest yearly production capacities.

Water management is crucial for the performance of anion exchange membrane water electrolyzers (AEM-WEs) to maintain membrane hydration and enable phase separation between hydrogen gas and liquid water. Therefore careful material selection for the anode and cathode is essential to enhance reactant/product transport and optimize water management under ‘dry cathode’ conditions. This study investigates the wetting characteristics of two commercially available porous transport layers (PTLs) used in AEM-WE: carbon paper and carbon paper with a microporous layer (MPL). Wettability was measured under static quasi-static and dynamic conditions to assess the effect of water and electrolytes (NaOH KOH K2CO3) across concentrations (up to 1 M) and operational temperatures (20 °C to 92 °C). Carbon paper exhibits mild hydrophobicity (advancing contact angles of ∼120° however with receding contact angle ∼0°) whereas carbon paper with MPL demonstrates superhydrophobicity (advancing and receding contact angles >145° and low contact angle hysteresis) maintaining a stable Cassie-Baxter wetting state. Dynamic wetting experiments confirmed the robustness of the superhydrophobicity in carbon paper with MPL facilitating phase separation between hydrogen gas and liquid water. The presence of supporting electrolytes did not significantly affect wettability and the materials retained hydrophobic properties across different temperatures. These findings highlight the importance of MPLs in optimizing water transport and gas rejection within AEM-WEs ensuring efficient and stable operation under “dry cathode” conditions. These PTLs (with and without the addition of the MPL) were integrated into AEM-WE and polarization curves were run. Preliminary data in a specific condition suggested the presence of the MPL within the PTL enhance AEM-WE performance.

Within energy system analysis there is discourse regarding the role and economic benefits of nuclear energy in terms of overall system costs. The reported findings range from considerable drawbacks to substantial benefits depending on the chosen models scenarios and underlying assumptions. This article addresses existing gaps by demonstrating how subtle variations in model assumptions significantly impact analysis outcomes. Historically uncertainties associated with nuclear energy costs have been well documented whereas renewable energy costs have steadily declined and have been relatively predictable. However as land availability increasingly constrains future renewable expansion development is shifting from onshore to offshore locations where cost uncertainties are greater and anticipated cost reductions are less reliable. This study emphasizes this fundamental shift highlighting how uncertainties in future renewable energy costs could strengthen the economic case of nuclear energy within fully integrated sector-coupled energy systems especially when the costs of all technologies and weather conditions are set in the moderate range. Focusing specifically on Denmark this article presents a thorough sensitivity analysis of renewable energy costs and weather conditions within anticipated future ranges providing a nuanced perspective on the role of nuclear energy. Ultimately the findings underscore that when examining total annual system costs the differences between scenarios with low and high nuclear energy shares are minimal and are within ±5 % for the baseline assumptions while updated adjustments reduce this variation to ±1 %.

Hydrogen production from water electrolysis can not only reduce greenhouse gas emissions but also has abundant raw materials which is one of the ideal ways to produce hydrogen from new energy. The hydrogen production power supply is the core component of the new energy electrolytic water hydrogen production device and its characteristics have a significant impact on the efficiency and purity of hydrogen production and the service life of the electrolytic cell. In essence the DC/DC converter provides the large current required for hydrogen production. For the converter its input still needs the support of a DC power supply. Given the maturity and technical characteristics of new energy power generation integrating energy storage into offshore energy systems enables stable power supply. This configuration not only mitigates energy fluctuations from renewable sources but also further reduces electrolysis costs providing a feasible pathway for large-scale commercialization of green hydrogen production. First this paper performs a simulation analysis on the wind–solar hybrid energy storage power generation system to demonstrate that the wind–solar–storage system can provide stable power support. It places particular emphasis on the significance of hydrogen production power supply design—this focus stems primarily from the fact that electrolyzers impose specific requirements on high operating current levels and low current ripple which exert a direct impact on the electrolyzer’s service life hydrogen production efficiency and operational safety. To suppress the current ripple induced by high switching frequency and high output current traditional approaches typically involve increasing the output inductor. However this method substantially increases the volume and weight of the device reduces the rate of current change and ultimately results in a degradation of the system’s dynamic response performance. To this end this paper focuses on developing a virtual impedance control technology aiming to reduce the ripple amplitude while avoiding an increase in the filter inductor. Owing to constraints in current experimental conditions this research temporarily relies on simulation data. Specifically a programmable power supply is employed to simulate the voltage output of the wind–solar–storage hybrid system thereby bringing the simulation as close as possible to the actual operating conditions of the wind–solar–storage hydrogen production system. The experimental results demonstrate that the proposed method can effectively suppress the ripple amplitude maintain high operating efficiency and ultimately meet the expected research objectives. That makes it particularly suitable as a high-quality power supply for offshore hydrogen production systems that have strict requirements on volume and weight.

Achieving net-zero emissions requires major changes across a nation’s economy energy and land systems particularly due to sectors where emissions are difficult to eliminate. Here we adapt two global scenarios from the International Energy Agency—the net-zero emissions by 2050 and the Stated Policies Scenario—using an integrated numerical economic-energy model tailored to Australia. We explore how emissions may evolve by sector and identify key technologies for decarbonisation. Our results show that a rapid shift to near-zero emissions electricity is central to reducing costs and enabling wider emissions reductions. From 2030 onwards carbon removal through land management and engineered solutions such as direct air capture and bioenergy with carbon capture and storage becomes critical. Australia is also well-positioned to become a global supplier of clean energy such as hydrogen made using renewable electricity helping reduce emissions beyond its borders.

This study explores a multi-faceted approach to improving the combustion performance and emission characteristics of a single-cylinder four-stroke direct injection (DI) compression ignition engine through the combined effects of butanol enrichment green-synthesized copper oxide (CuO) nanoparticles and hydrogen supplementation. The baseline fuel was a B20 biodiesel blend further enriched with 10 % butanol to enhance oxygen availability and atomization. CuO nanoparticles were synthesized via an eco-friendly aloe vera extractmediated method and dispersed into the fuel to promote oxidation kinetics and stabilize combustion. Experimental results revealed that the B20+But10 %+CuO100 blend achieved the highest brake thermal efficiency (BTE) of 33.6 % at full load alongside notable reductions in carbon monoxide (CO) unburned hydrocarbons (HC) nitrogen oxides (NOx) and smoke opacity compared to neat B20. Reactivity controlled compression ignition (RCCI) trials further demonstrated that hydrogen enrichment at 5 LPM and 10 LPM improved flame propagation Brake thermal efficiency (33.89 % & 35.43 %) and reduced brake-specific fuel consumption of nearly 10 % (0.26 Kg/KWh) & 0.25 Kg/KWh). While excessive hydrogen supply (10 LPM) marginally increased HC emissions (110 PPM) at higher loads due to localized incomplete oxidation overall results confirm significant emission mitigation. The findings highlight that the synergistic integration of butanol oxygenation catalytically active CuO nanoparticles and optimized hydrogen enrichment offers a viable pathway toward cleaner combustion improved energy efficiency and reduced pollutant emissions in biodiesel-fueled CI engines.

Ammonia represents a promising alternative fuel and hydrogen carrier for power generation due to its advantages in storage and transportation compared to those of hydrogen. However challenges persist in the direct use of ammonia in solid oxide fuel cells (SOFCs) particularly with respect to performance degradation—an issue that necessitates comprehensive investigation at the full-stack scale. This study examines a ten-cell full-size SOFC stack under various operating conditions to evaluate the viability of ammonia as a direct fuel. Experiments were conducted using pure ammonia pure hydrogen fully reformed ammonia and 50 % pre-reformed ammonia at three operating temperatures (660◦C 710 ◦C and 760 ◦C). Performance was characterized through current–voltage curves electrochemical impedance spectroscopy and continuous monitoring of residual ammonia in the exhaust using Fourier-transform infrared spectroscopy. A 200-hour durability test was performed to assess long-term stability. The results demonstrated that at temperatures of ≥ 710 ◦C ammonia-fueled SOFCs performed comparably to hydrogen-fueled configurations within typical operating ranges (0.2–0.5 A/cm2 ). The stack achieved optimal performance at 55–80 % fuel utilization. The ammonia-fueled configurations exhibited different voltage behaviors at higher fuel utilizations compared with those of the hydrogen-fueled configurations. The residual ammonia concentration in the anode off-gas remained well below the safety thresholds. Long-term testing demonstrated an initial degradation that eventually stabilized at a more sustainable rate. These findings validate ammonia as a viable fuel for SOFC stacks when operated at appropriate temperatures (≥710 ◦C) and optimal fuel utilization offering a pathway toward sustainable carbon-free ammonia energy systems.

This study develops and applies a life cycle assessment (LCA) framework combined with predictive market models to evaluate the environmental impacts of electricity and hydrogen for transport in the EU27+UK from 2020 to 2050. By linking evolving power sector scenarios with hydrogen supply models we assess the wellto-wheels (WTW) performance of battery electric vehicles (BEVs) and fuel cell electric vehicles (FCEVs) under consistent energy assumptions. Results show that electricity decarbonization can reduce GWP by up to 80% by 2050 but increases land use and mineral/metal demand due to renewable infrastructure expansion. The environmental impacts of hydrogen production are strongly influenced by the electricity mix especially in high electrolysis scenarios. WTW analysis indicates that while BEVs consistently achieve lower WTW GWP than FCEVs across all scenarios both drivetrains exhibit notable trade-offs in other impact categories. Scenarios dominated by blue hydrogen although not optimal in terms of GWP present a more balanced environmental profile making them a viable transitional pathway in contexts that prioritize minimizing other environmental impacts.

The thermal management system and the balance-of-plant (BoP) in fuel cell electric vehicles (FCEV) are characterized by a particularly high level of complexity and a number of interfaces. Optimizing the efficiency of the overall vehicle is of special importance to maximize the range and increase the attractiveness of this technology to customers. This paper focuses on the optimization potential of the air supply system in the BoP whereby the charging concepts of the electric supercharger (ESC) and the electrically assisted turbocharger (EAT) as well as the integration of water spray injection (WSI) at the compressor inlet are investigated in the framework of an FCEV complete vehicle co-simulation. As a benchmark for the integration of these optimization measures the complete vehicle co-simulation is designed for a fuel cell electric passenger car of the current generation. Here thermo-hydraulic fluid circuits in the thermal management software KULI are coupled with mathematical-physical models in MATLAB/Simulink. Applying advanced simulation methodologies for the components of fuel cell powertrain and vehicle cabin enables the mapping of the effects of realistic operating conditions on the FCEV characteristics. The EAT offers the advantage over the ESC that due to the arrangement of an exhaust gas turbine a part of the exhaust gas enthalpy flow downstream of the fuel cell stack can be recovered which reduces the electrical compressor drive power. Moreover an additional reduction of this power consumption can be achieved by WSI as the effect of evaporative cooling lowers the initial compression temperature. For analysis and comparison these concepts are again modeled with high degree of detail and integrated into the benchmark overall vehicle simulation. The results indicate considerable reductions in the electric compressor drive power of the EAT compared to the ESC with noteworthy potential for reducing the vehicle’s hydrogen consumption. At an operating point in Worldwide harmonized Light Duty Test Cycle (WLTC) under 35 ◦ C ambient temperature and 25 % relative humidity the electrical compressor drive power shows a reduction potential of −40 % which corresponds to a vehicle-level hydrogen consumption reduction of up to −3 %. In addition the results also highlight the effect of the WSI in both charging concepts whereby its potential to reduce the hydrogen consumption on the overall vehicle level is relatively small. In WLTC at 35 ◦C ambient temperature and 25 % relative humidity the compressor drive power reduction potential for ESC and EAT averages −5 % while the effect on hydrogen consumption is only around −0.25 %.

Clean hydrogen (H2) is highly desirable for the sustainable development of society in the era of carbon neutrality. However the current capability of water electrolysis and steam methane (CH4) reforming to produce green and blue H2 is very limited mainly due to the high production cost difficult scale-up technology or operational risk. Here we propose the direct catalytic decomposition of diesel using a nano-Fe-based catalyst to produce the so-called ‘‘jadeite H2” while simultaneously fixing the carbon from the diesel in the form of carbon nanotubes (CNTs). Efforts are made to understand the suppression mechanism of the CH4 byproduct such as by tuning the catalyst type space velocity and reaction time. The optimal green index (GI)—that is the molar ratio of H2/carbon in a gaseous state—of the proposed technology exceeds 42 which is far higher than those of any previously reported chemical vapor deposition (CVD) method. Moreover the carbon footprint (CFP) of the proposed technology is far lower than those of grey H2 blue H2 and other dehydrogenation technologies. Compared with most of the technologies mentioned above the energy consumption (per mole of H2) and reactor amplification of the proposed technology validate its high efficiency and great practical feasibility.

As the global push for carbon neutrality accelerates energy efficiency has become essential for sustainable development especially for nations like Nigeria that face rising energy demands and significant environmental challenges. This study explores how integrating energy efficiency with carbon neutrality can support Nigeria’s strategic energy goals while offering global lessons for other countries facing similar challenges focusing on key sectors including industry transport and power generation. The study systematically examines the impacts of renewable energy (RE) technologies like solar wind and hydropower—alongside policy reforms technological innovations and demand-side management strategies to advance energy efficiency in Nigeria. Key findings include the identification of strategic policy frameworks technological solutions and the transformative role of green hydrogen in decarbonizing hard-to-electrify sectors. The study also emphasizes the importance of international climate finance decentralized RE systems like solar mini-grids for improving energy access and economic opportunities for job creation in the RE sector. Furthermore it highlights the need for behavioral changes community engagement and consistent policy implementation to address infrastructure gaps and drive energy efficiency goals. The novelty of this research lies in its scenario-based analysis of Nigeria’s low-carbon transition detailing both the opportunities and challenges such as policy inconsistencies infrastructure deficits and financial constraints. The findings stress the importance of international collaboration technological advancements and targeted investments to overcome these challenges. By offering actionable insights and strategic recommendations this study provides a roadmap for policymakers industry stakeholders and researchers to drive Nigeria towards a sustainable carbon-neutral future by 2050.

This paper presents QDQN-ThermoNet a novel Quantum-Driven Dual Deep Q-Network framework for intelligent thermal regulation in next-generation electric vehicles with hybrid energy systems. Our approach introduces a dual-agent architecture where a classical DQN governs solid-state battery thermal management while a quantumenhanced DQN regulates proton exchange membrane fuel cell dynamics both sharing a unified quantumenhanced experience replay buffer to facilitate cross-system information transfer. Hardware-in-the-Loop validation across diverse operational scenarios demonstrates significant performance improvements compared to classical methods including enhanced thermal stability (95.1 % vs. 82.3 %) faster thermal response (2.1 s vs. 4.7 s) reduced overheating events (0.3 vs. 3.2) and superior energy efficiency (22.4 % energy savings). The quantum-enhanced components deliver 38.7 % greater sample efficiency and maintain robust performance under sparse data conditions (33.9 % improvement) while material-adaptive control strategies leveraging MXeneenhanced phase change materials achieve a 50.3 % reduction in peak temperature rise during transients. Component lifetime analysis reveals a 33.2 % extension in battery service life through optimized thermal management. These results establish QDQN-ThermoNet as a significant advancement in AI-driven thermal management for future electric vehicle platforms effectively addressing the complex challenges of coordinating thermal regulation across divergent energy sources with different optimal operating temperatures.

In response to the growing global interest in hydrogen as an energy carrier this study provides the first attempt to develop a baseline inventory of U.S. hydrogen emissions from production distribution and storage. The scope of this study was limited to pure hydrogen emissions and excludes emissions from low purity hydrogen streams and carriers. A detailed literature search was conducted utilizing various greenhouse gas emissions inventory protocol principles and guidelines to consolidate a list of activity data and emission factors. The best available activity data and emission factors were then selected via a Multi-Criteria-Based Decision Making Method named Technique for Order Preference by Similarity to Ideal Solution or modelled using best-engineering estimates. The study estimated total U.S. hydrogen emissions of 0.063 MMTA with emission bounds ranging from 0.02 to 0.11 MMTA. Given the total estimated H2 production capacity of 7.97 MMTA the study estimates a total U.S. hydrogen emission rate for production distribution and storage of 0.79% (0.26%–1.32%). To reduce the uncertainty in the estimated total hydrogen emissions future work should be conducted to measure facility-level hydrogen emission factors across multiple sectors. The inventory framework developed in this study can serve as a living document that can be updated and enhanced as more empirical data is obtained. This study also provides detailed insights regarding key emission or leakage sources and causes from each supply chain stage. The insights and conclusions from this study can provide direction for hydrogen production companies and safety professionals as they develop hydrogen emission mitigation measures and controls.

This study investigates numerically combustion attributes and NOx formation of premixed ammonia-hydrogen/air flames within a swirl burner of a gas turbine considering various conditions of hydrogen fraction (HF: 0 % 5 % 30 % 40 % and 50 %) equivalence ratio (φ: 0.85 1.0 and 1.2) and mixture inlet temperature (Tin: 400–600 K). The results illustrate that flame temperature increases with hydrogen addition from 1958 K for pure ammonia to 2253 K at 50 % HF. Raising the inlet temperature from 400 K to 600 K markedly enhances combustion intensity resulting in an increase of the Damköhler number (Da) from 117 to 287. NOx levels rise from ∼1800 ppm (0 % HF) to ∼7500 ppm (50 % HF) and peak at 8243 ppm under lean conditions (φ = 0.85). Individual NO N2O and NO2 emissions also reach maxima at φ = 0.85 with values of 5870 ppm 2364 ppm and 10 ppm respectively decreasing significantly under richer conditions (2547 ppm 1245 ppm and 5 ppm at φ = 1.2). These results contribute to advancing low-carbon fuel technologies and highlight the viability of ammonia-hydrogen co-firing as a pathway toward sustainable gas turbine operation.

The development of large-scale flexible and safe hydrogen storage is critical for enabling a low-carbon energy system. Deep saline aquifers (DSAs) offer substantial theoretical capacity and broad geographic distribution making them attractive options for underground hydrogen storage. However hydrogen storage in DSAs presents complex technical geochemical microbial geomechanical and economic challenges that must be addressed to ensure efficiency safety and recoverability. This study synthesizes current knowledge on hydrogen behavior in DSAs focusing on multiphase flow dynamics capillary trapping fingering phenomena geochemical reactions microbial consumption cushion gas requirements and operational constraints. Advanced numerical simulations and experimental observations highlight the role of reservoir heterogeneity relative permeability hysteresis buoyancy-driven migration and redox-driven hydrogen loss in shaping storage performance. Economic analysis emphasizes the significant influence of cushion gas volumes and hydrogen recovery efficiency on the levelized cost of storage while pilot studies reveal strategies for mitigating operational and geochemical risks. The findings underscore the importance of integrated coupled-process modeling and comprehensive site characterization to optimize hydrogen storage design and operation. This work provides a roadmap for developing scalable safe and economically viable hydrogen storage in DSAs bridging the gap between laboratory research pilot demonstration and commercial deployment.

This study presents a comprehensive review of the viability of hydrogen as an energy carrier for offshore wind energy compared to existing electricity carrier systems. To enable a state-of-the-art system comparison a review of wind-to-hydrogen energy conversion and transmission systems is conducted alongside wind-to-electricity systems. The review reveals that the wind-to-hydrogen energy conversion and transmission system becomes more cost-effective than the wind-to-electricity conversion and transmission system for offshore wind farms located far from the shore. Electrical transmission systems face increasing technical and economic challenges relative to the hydrogen transmission system when the systems move farther offshore. This study also explores the feasibility of using seawater for hydrogen production to conserve freshwater resources. It was found that while this approach conserves freshwater and can reduce transportation costs it increases overall system costs due to challenges such as membrane fouling in desalination units. Findings indicated that for this approach to be sustainable proper management of these challenges and responsible handling of saline waste are essential. For hydrogen energy transmission this paper further explores the potential of repurposing existing oil and gas pipeline infrastructure instead of constructing new pipelines. Findings indicated that with proper retrofitting the existing natural gas pipelines could provide a cost-effective and environmentally sustainable solution for hydrogen transport in the near future.

This paper explores how the deployment of “High-Performance Heat-Powered Heat Pumps” (HP3 s)—a novel heating technology—could help meet the domestic heating demand in the UK and reduce how much grid-scale energy storage is needed in comparison to a scenario where electrical heat pumps fully supply the heating demand. HP3 systems can produce electricity which can partially alleviate the stress caused by electrical heat pumps. A parametric analysis focusing on two variables the penetration of HP3 systems (H) and the amount of electricity exported (Ɛ) is presented. For every combination of H and Ɛ the electricity system is optimized to minimize the cost of electricity. Three parameters define the electricity system: the generation mix the energy storage mix and the amount of over-generation. The cost of electricity is at its highest when electrical heat pumps supply all demand. This reduces as the penetration of HP3 systems increases due to a reduction in the need for energy storage. When HP3 systems supply 100% of the heating demand the total cost of electricity and the storage capacity needed are 6% and 50% lower respectively compared to a scenario where electrical heat pumps are in 100% of residences.

As global efforts to decarbonize intensify hydrogen produced via renewable electricity has emerged as a pivotal energy vector for a sustainable industrial future. This commentary provides a critical analysis of the current state of the hydrogen economy in Europe detailing the core principles operational mechanisms and industrial status of four primary water electrolysis technologies: alkaline (ALK) proton exchange membrane (PEM) solid oxide (SOEC) and anion exchange membrane (AEM). Furthermore it explores the significant socio-political challenges inherent in producing green hydrogen in non-EU nations for subsequent import into the European market.

Coal constitutes China’s most significant resource endowment at present. Utilizing coal resources for hydrogen production represents an early-stage pathway for China’s hydrogen production industry. The analysis of energy quality and carbon emissions in coal gasification-based hydrogen production holds practical significance. This paper integrates the exergy analysis methodology into the traditional LCA framework to evaluate the exergy and carbon emission scales of coal gasification-based hydrogen production in China considering the technical conditions of CCUS. This paper found that the life cycle exergic efficiency of the whole chain of gasification-based hydrogen production in China is accounted to be 38.8%. By analyzing the causes of exergic loss and energy varieties it was found that the temperature difference between the reaction of coal gasification and CO conversion unit and the pressure difference due to the compressor driven by the electricity consumption of the compression process in the variable pressure adsorption unit are the main causes of exergic loss. Corresponding countermeasures were suggested. Regarding decarbonization strategies the CCUS process can reduce CO2 emissions across the life cycle of coal gasification-based hydrogen production by 48%. This study provides an academic basis for medium-to-long-term forecasting and roadmap design of China’s hydrogen production structure.

The adoption of hydrogen as a clean energy carrier depends heavily on the development of materials capable of enduring the extreme conditions associated with its production storage and transportation. This review critically evaluates the performance of metals polymers and composites in hydrogen-rich environments focusing on degradation mechanisms such as hydrogen embrittlement rapid gas decompression and long-term fatigue. Metals like carbon steels and high-strength alloys can experience a 30–50 % loss in tensile strength due to hydrogen exposure while polymers suffer from permeability increases and sealing degradation. Composite materials though strong and lightweight may lose up to 15 % of their mechanical properties over time in hydrogen environments. The review highlights current mitigation strategies including hydrogen-resistant alloys polymer blends protective coatings composite liners and emerging technologies like predictive modeling and AI-based material design. With hydrogen production expected to reach 500 GW globally by 2030 improving material compatibility and developing international standards are essential for scaling hydrogen infrastructure safely and cost-effectively. This work presents an integrated analysis of material degradation mechanisms highlights key challenges across metals polymers and composites in hydrogen environments and explores recent innovations and future strategies to enhance durability and performance in hydrogen infrastructure.

Clean energy technologies offer promising pathways for low-carbon transitions yet their feasibility remains uncertain particularly in rapidly developing regions. This study develops a Factorial Multi-Stochastic Optimization-driven Equilibrium (FMOE) model to assess the economic and environmental impacts of clean power deployment. Using Small Modular Reactors (SMRs) in Guangdong China as a case study the model reveals that SMRs can reduce system costs and alleviate GDP losses supporting provincial-level Nationally Determined Contributions (NDCs). If offshore wind capital costs fall to 40 % of SMRs’ SMR deployment may no longer be necessary after 2030. Otherwise SMRs could supply 22 % of capacity by 2040. The FMOE model provides a robust adaptable framework for evaluating emerging technologies under uncertainty and supports sustainable power planning across diverse regional contexts. This study offers valuable insights into the resource and economic implications of clean energy strategies contributing to global carbon neutrality and efficient energy system design.

This study presents a cross-national investigation into the drivers and psychological mechanisms shaping public perceptions and acceptance of hydrogen refuelling infrastructure located in residential proximity. Parallel survey data from Japan Spain and Norway were analysed using a multigroup comparative framework. Measurement invariance was established across the three datasets subject to minor modifications within the constructs of trust in hydrogen innovation safe housing concern and perceived usefulness. The conceptual models yielded generalisable findings across countries: negative emotions exerted a stronger influence on individuals' risk perceptions than positive emotions whereas perceived usefulness had a greater impact on acceptance than perceived risk. Safe housing and environmental concerns exhibited moderating effects that amplified the influence of affective responses towards hydrogen refuelling facilities with varying magnitudes across datasets. Furthermore the incorporation of Hofstede's cultural dimensions provided insights into cross-country differences revealing that individualism uncertainty avoidance and long-term orientation explain the psychological pathways through which affective states are translated into subjective evaluations of hydrogen facilities ultimately shaping community acceptance.

Hydrogen (H2) is an attractive fuel due to its high specific energy and zero direct carbon emissions. Membraneless electrolyzers (MEs) offer a lower-cost route to hydrogen production but their operation is complex and current efficiencies are modest. Although multi-objective optimization is widely used its heavy compute demands and weak integration with modern learning methods limit scalability and adaptability. We introduce a practical ML-guided way to design Tesla-valve (TV) membraneless electrolyzers by building diodicity (Di) directly into the geometry search. Using multilayer-perceptron surrogates trained on 150 high-fidelity simulations (R2 > 0.95) we link four design knobs (We Wc Wd Di) to pressure drop (Δp) and ohmic loss. A Genetic Algorithm (GA)-based multi-objective search over realistic ranges delivers 60 Pareto-optimal designs that make the Δp–ohmic trade-off explicit; TOPSIS then selects a balanced geometry (We = 1.708 mm Wc = 0.200 mm Wd = 1.012 mm Di = 1.618) with ohmic loss 4.069 V and Δp 6.169 Pa. The approach delivers faster lower-cost design maps and is supported by experimental checks pointing to an actionable route for scalable interpretable optimization of sustainable hydrogen production.

Refrigeration units in semi-trucks or rigged-body trucks have an energy demand of 8.2–12.4 MWh/y and emit 524.26 kt CO2e/y in Germany. Electrification with fuel cell systems reduces the CO2 emission but an increase of efficiency is necessary because of rapidly increasing hydrogen costs. A metal hydride refrigeration system can increase the efficiency. Even though it was already demonstrated in lab scale with 900 W this power is not sufficient to support a truck refrigeration system and the power output of the lab system was not controllable. Here we show the design and validation of a MATLAB© Simulink model of this metal hydride refrigeration system and its suitability for high power applications with a scaled-up reactor. It was scaled up to rated power of 5 kW and efficiency improvements with an advanced valve switching as well as a controlled cooling pump were implemented. Two application-relevant use cases with hydrogen mass flows from hydrogen fuel cell truck systems were analyzed. The simulation results of these use cases provide an average cooling power of 4.2 and 6.1 kW. Additionally the control of the coolant mass flow at different temperature levels a controlled hydrogen mass flow with a bypass system and an advanced valve switching mechanism increased the system efficiency of the total refrigeration system by 30 % overall.

A hybrid energy system (HES) integrates various energy resources to attain synchronized energy output. However HES faces significant challenges due to rising energy consumption the expenses of using multiple sources increased emissions due to non-renewable energy resources etc. This study aims to develop an energy management strategy for distribution grids (DGs) by incorporating a hydrogen storage system (HSS) and demand-side management strategy (DSM) through the design of a multi-objective optimization technique. The primary focus is on optimizing operational costs and reducing pollution. These are approached as minimization problems while also addressing the challenge of achieving a high penetration of renewable energy resources framed as a maximization problem. The third objective function is introduced through the implementation of the demand-side management strategy aiming to minimize the energy gap between initial demand and consumption. This DSM strategy is designed around consumers with three types of loads: sheddable loads non-sheddable loads and shiftable loads. To establish a bidirectional communication link between the grid and consumers by utilizing a distribution grid operator (DGO). Additionally the uncertain behavior of wind solar and demand is modeled using probability distribution functions: Weibull for wind PDF beta for solar and Gaussian PDF for demand. To tackle this tri-objective optimization problem this work proposes a hybrid approach that combines well-known techniques namely the non-dominated sorting genetic algorithm II and multi-objective particle swarm optimization (Hybrid-NSGA-II-MOPSO). Simulation results demonstrate the effectiveness of the proposed model in optimizing the tri-objective problem while considering various constraints.

Marine and island power systems usually incorporate various forms of energy supply which poses challenges to the coordinated control of the system under diverse irregular and complex load operation modes. To improve the stability and self-sufficiency of island-isolated microgrids with high penetration of renewable energy this study proposes a coordinated control strategy for an island microgrid with PV HGT and HESS combining primary power allocation via low-pass filtering with a fuzzy logic-based secondary correction. The fuzzy controller dynamically adjusts power distribution based on the states of charge of the battery and supercapacitor following a set of predefined rules. A comprehensive system model is developed in Matlab R2023b integrating PV generation an electrolyzer HGT and a battery–supercapacitor HESS. Simulation results across four operational cases demonstrate that the proposed strategy reduces DC bus voltage fluctuations to a maximum of 4.71% (compared to 5.63% without correction) with stability improvements between 0.96% and 1.55%. The HESS avoids overcharging and over-discharging by initiating priority charging at low SOC levels thereby extending service life. This work provides a scalable control framework for enhancing the resilience of marine and island microgrids with high renewable energy penetration.

This bibliometric analysis aims to map the evolution disciplinary structure and collaboration dynamics of green hydrogen (GH) research in North Africa from 2019 to 2025. Drawing on a corpus of ~39000 global publications indexed in Scopus and analysed through SciVal we isolate and examine the contributions of Egypt Morocco Algeria Tunisia and Libya. Egypt leads the region with 842 publications and a field-weighted citation impact of 2.42 followed by Morocco (232 Pubs. FWCI 2.30) and Algeria (184 Pubs. FWCI 1.65). Notably Tunisia exhibits the highest growth factor (41 times since 2019) while Libya remains marginal with only 18 publications in the GH field. The region is well represented in Energy and Environmental fields but is underrepresented in trendy areas such as Materials and Chemical Engineering highlighting critical gaps in consistency sophistication and technical infrastructure. While international collaboration exceeds 69% for most countries it rarely translates into a high impact compared to the global average. Conversely the limited industrial collaboration shows the highest citation impact (e.g. Tunisia: 68 citations/publications). A thematic analysis reveals shared strengths in electrolytic hydrogen production and renewable energy integration with Egypt showing diversification into microalgae and nanocomposites and Morocco excelling in techno-economic assessments and ammonia-based systems. By revealing patterns in research quality collaboration and thematic positioning this study offers evidence-based insights to inform national science strategies enhance regional cooperation and position North Africa more strategically in the emerging global green hydrogen economy.

This study investigates hydrogen storage enhancement through adsorption in porous materials by coupling the Dubinin–Astakhov (D-A) adsorption model with H2 conservation equations (mass momentum and energy). The resulting system of partial differential equations (PDEs) was solved numerically using the finite element method (FEM). Experimental work using activated carbon as an adsorbent was carried out to validate the model. The comparison showed good agreement in terms of temperature distribution average pressure of the system and the amount of adsorbed hydrogen (H2). Further simulations with different adsorbents indicated that compact metal–organic framework 5 (MOF-5) is the most effective material in terms of H2 adsorption. Additionally the pair (273 K 800 s) remains the optimal combination of injection temperature and time. The findings underscore the prospective advantages of optimized MOF-5-based systems for enhanced hydrogen storage. These systems offer increased capacity and safety compared to traditional adsorbents. Subsequent research should investigate multi-objective optimization of material properties and system geometry along with evaluating dynamic cycling performance in practical operating conditions. Additionally experimental validation on MOF-5-based storage prototypes would further reinforce the model’s predictive capabilities for industrial applications.

Achieving the 1.5 ◦C global temperature target and reaching net-zero emissions by 2050 require a fundamental transformation of energy systems driven by the rapid deployment of renewable energy technologies and underpinned by systemic policy financial and infrastructural reform. The manuscript adopts a literature-driven approach synthesizing findings from existing scholarly sources that shape the transition to sustainable energy systems. It begins by outlining global progress toward climate targets emphasizing the critical role of renewable energy in decarbonizing electricity industry and transport sectors. The manuscript explores recent technological advancements and trends in solar wind hydrogen and emerging clean technologies highlighting their impact on global energy supply chains and production models. Particular attention is given to the complexities of integrating renewable energy into existing infrastructure including grid modernization digitaliation and storage technologies. On the demand side the article examines changing consumption patterns electrification and the role of distributed generation in shaping future energy landscapes. Investment and finance emerge as central challenges with the paper analyzing the disparities in capital costs between developed and developing economies and the need for innovative green finance instruments to de-risk investment. The manuscript further identifies structural barriers including policy uncertainty supply chain constraints and permitting delays as key impediments to progress. Nonetheless the article outlines significant opportunities for scaling up renewable deployment through international cooperation targeted subsidies and public-private partnerships. The manuscript concludes by emphasizing the necessity of coherent and enforceable policy frameworks to align national commitments with global climate goals. It calls for an integrated multi-stakeholder approach to ensure that finance infrastructure demand and governance evolve in tandem thereby enabling a just inclusive and resilient global energy transition.

This review evaluates the current state of the art on polymeric materials for hydrogen transportation and storage highlighting the importance of developing a sustainable hydrogen infrastructure worldwide. It analyses different polymeric materials used for hydrogen transportation and storage applications including high-density polyethylene (HDPE) polytetrafluoroethylene (PTFE) polyimides (PI) polyether ether ketone (PEEK) polyamide ethylene propylene diene monomer (EPDM) polyvinylidene fluoride (PVDF) and fluorinated ethylene propylene (FEP). These materials are assessed using key characteristics such as hydrogen permeability mechanical strength chemical resistance and thermal stability. The review finds that while PEEK and polyimides exhibit the highest thermal stability (up to 400 °C) and pressure resistance (300–400 bar) HDPE remains the most cost-effective option for low-pressure applications. PTFE and FEP offer the lowest hydrogen permeability (<0.01 cm³ mm/m²·day·bar) making them ideal for sealing and lining in hydrogen storage systems. Furthermore key research gaps are identified and suggestions for future research and development directions are outlined. This comprehensive review is a valuable resource for researchers and engineers working towards sustainable hydrogen infrastructure development.

This paper presents a multi-scale experimental investigation into the damage mechanisms in carbon fiberreinforced polyphthalamide (CF/PPA) composites subjected to hygrothermal aging. The study specifically targets their suitability for structural components in advanced hydrogen storage systems such as Type V pressure vessels. Polyphthalamides (PPAs) as semi-aromatic polyamides offer superior thermal stability chemical resistance and mechanical performance compared to conventional aliphatic polyamides making them promising candidates for structural components exposed to harsh environments. In order to simulate more severe environmental exposure accelerated hygrothermal aging tests were conducted at 50 ◦C in immersion. A range of microscopic to macroscopic characterization techniques were used to assess changes in mechanical performance and microstructural integrity. The analysis revealed that the CF/PPA composites retained good matrix ductility even after aging indicating the resilience of the semi-aromatic polyamide matrix under hygrothermal stress. Multi-scale damage analysis has been performed on both unaged and aged samples at 50 ◦C for various aging times. The dominant damage mechanism identified was decohesion at the fiber/matrix interface rather than bulk matrix degradation. This interfacial debonding has a significant impact on mechanical performance and is attributed to moisture-induced weakening of interfacial interactions. These findings emphasize the potential of CF/PPA composites for use in high-performance hydrogen storage applications while highlighting the critical need for interface-tailored designs to enhance environmental durability.

Aiming at the problems of poor transient characteristics of converter output DC voltage and large DC current ripple caused by alkaline electrolyzer (AEL) switching operation in the wind power-hydrogen coupled integrated system this paper proposes an interleaved parallel VDCM control method to improve the stable operation of the system. Firstly a refined mathematical-physical model of the wind power-hydrogen coupled integrated system including HD-PMSG interleaved parallel buck and AEL is constructed. Then the VDCM control strategy is introduced into the interleaved parallel buck converter which provides reliable inertia and damping support for the output voltage of the hydrogen production system by simulating the DC motor power regulation characteristics and effectively improving the current ripple of the output current. Meanwhile the influence of rotational inertia and the damping coefficient on the dynamic stability of the system in the control strategy is analyzed based on the small signal method. Finally the proposed method is validated through MATLAB/SIMULINK simulation experiments and RCP + HIL hardware-in-the-loop experiments. The results show that the proposed method can improve the dynamic stability of the wind power-hydrogen coupled integrated system effectively.

The cement industry a foundation of infrastructure development is responsible for nearly 7 % of global CO2 emissions highlighting an urgent need for scalable decarbonization strategies. This study investigates the technoeconomic feasibility of integrating on-site solar-powered green hydrogen production into cement manufacturing processes. A mixed-integer linear programming (MILP) model optimizes the design and operation of solar photovoltaics (PV) proton exchange membrane (PEM) electrolyzer and hydrogen storage for a representative cement plant in Texas. Five hydrogen substitution scenarios (10–30 % of thermal demand) were evaluated based on net present cost (NPC) levelized cost of hydrogen (LCOH) cost of CO2 avoided and greenhouse gas (GHG) emissions reduction. Hydrogen integration up to 30 % is technically viable but economically constrained with LCOH rising non-linearly from $58.7 to $95.3 GJ− 1 due to escalating component costs. Environmentally a 30 % hydrogen share could reduce total U.S. cement sector emissions by 22 %. While significant this confirms at present the solar-driven hydrogen serves as a partial solution rather than a standalone pathway to deep decarbonization suggesting it must complement other strategies like carbon capture electrification and other complementary technologies. The economic viability of this approach is entirely contingent on financial incentives as the investment tax credits of 80 % or higher are essential to enable cost parity with fossil fuels. This work provides a comprehensive techno-economic and environmental framework concluding immense economic barriers and that aggressive policy support is indispensable for enabling the transition to low-carbon cement manufacturing.

This study evaluates the techno-economic performance of hybrid renewable microgrids integrating hydrogen storage and fuel cells in two Moroccan pilot farms: a grid-connected site (BLFARM) and an off-grid site (RIMSAR). Real meteorological and load data were analyzed in HOMER Pro to assess feasibility. In 2024 BLFARM achieved a Levelized Cost of Energy (LCOE) of e1.63/kWh and a Renewable Fraction (Ren Frac) of 83.9% while RIMSAR reached e4.32/kWh with 100% renewable contribution. Hydrogen use remained limited due to low demand and high costs. Assuming 2050 hydrogen-technology reductions LCOE decreased to e0.160/kWh (BLFARM) and e0.425/kWh (RIMSAR) while hydrogen components were still underutilized. Aggregating demand from 5-80 farms reduced LCOE by over 50% from e0.093 to e0.045/kWh (BLFARM) and from e0.142 to e0.074/kWh (RIMSAR) while increasing electrolyzer and fuelcell operation. Community-networked hydrogen microgrids thus enhance component utilization energy resilience and cost effectiveness in rural Moroccan agriculture.

A well-developed hydrogen infrastructure is a key element for the global energy transition. The strategic implementation of this infrastructure is challenging due to the wide range of different criteria which need to be considered and analyzed. This paper presents a novel multi-criteria analysis framework for the optimal localization of power-to-gas (PtG) plants. The framework considers criteria such as renewable energy availability hydrogen demand proximity to existing gas infrastructure and groundwater availability. A techno-economic model is integrated into the framework to evaluate the levelized cost of hydrogen (LCOH) for different electrolyzer technologies. Applying the developed framework to Germany the potential of northern and northwestern Germany as suitable locations becomes apparent. In addition LCOH for PtG plants at selected locations in Germany are evaluated depending on the year of commissioning. The large differences between present LCOH ranging from 16.8 €/kg to 9.1 €/kg illustrate the importance of an integrated techno-economic model.

Due to the lower radiative fraction and typically higher storage pressures gas temperatures can often result in longer safety distances compared to radiative heat transfer for hydrogen jet flames. The high temperatures however also lead to a low density causing the flow to rise at a certain distance from the release. Unfortunately a model to determine this distance similar to what is available for unignited releases is currently not available which this paper aim to provide. An experimental study was conducted investigating the buoyancy effect on ignited horizontal hydrogen jet releases with different release diameters. The invisible hydrogen plume was visualized using a Background Oriented Schlieren technique (BOS). The transition of the initial momentumdriven jet into a fully buoyancy-driven jet was estimated by following the gradient of the centerline of the plume. A model based on the Froude number of the release similar to the model for unignited releases was developed and the distance showed a very similar dependence on the Froude number but giving consistently approximately 39% shorter distances.

High-temperature proton exchange membrane fuel cells (HT-PEM FCs) represent a promising avenue for generating carbon dioxide-free electricity through the utilization of hydrogen fuel. These systems present numerous advantages and challenges for mobile applications positioning them as pivotal technologies for the realization of emission-free regional aircraft. Efficient thermal management of such fuel cell-powered systems is crucial for ensuring the safe and durable operation of the aircraft while concurrently optimizing system volume mass and minimizing parasitic energy consumption. This paper presents four distinct heat transfer principles tailored for the FC-system of a conceptual hydrogen-electric regional aircraft exemplified by DLR’s H2ELECTRA. The outlined approaches encompass conductive cooling air cooling liquid cooling phase change cooling and also included is the utilization of liquid hydrogen as a heat sink. Approaches are introduced with schematic cooling architectures followed by a comprehensive evaluation of their feasibility within the proposed drivetrain. Essential criteria pertinent to airborne applications are evaluated to ascertain the efficacy of each thermal management strategy. The following criteria are selected for evaluation: safety ease of integration reliability and life-cycle costs technology readiness and development as well as performance which is comprised of heat transfer weight volume and parasitic power consumption. Of the presented cooling methods two emerged to be functionally suitable for the application in MW-scale aircraft applications at their current state of the art: liquid cooling utilizing water under high pressure or other thermal carrier liquids and phase-change cooling. Air cooling and conductive cooling have a high potential due to their reduced system complexity and mass but additional studies investigating effects at architecture level in large-scale fuel cell stacks are needed to increase performance levels. These potentially suitable heat transfer technologies warrant further investigation to assess their potential for complexity and weight reduction in the aircraft drivetrain.

Ammonia due to its favorable physicochemical properties is considered an effective hydrogen carrier enabling the storage of surplus energy generated from renewable sources. Large-scale implementation of this concept requires the safe transport of ammonia over long distances commonly achieved through pipeline systems—a practice with global experience dating back to the 1960s. However operational history demonstrates that failures in such infrastructures remain inevitable often leading to severe environmental consequences. This article reviews both passive and active methods for preventing and mitigating incidents in ammonia pipeline systems. Passive measures include the assessment of material compatibility with ammonia and the designation of adequate buffer zones. Active methods focus on leak detection techniques such as balance-based systems acoustic monitoring and ammonia-specific sensors. Additionally the article highlights the potential environmental risks associated with ammonia release emphasizing its contribution to the greenhouse effect as well as its adverse impacts on soil surface and groundwater and human health. By integrating historical lessons with modern safety technologies the article contributes to the development of reliable ammonia transport infrastructure for the hydrogen economy.

The hybrid energy storage system (HESS) that combines battery with hydrogen storage exploits complementary power/energy characteristics but most studies optimize capacity and operation separately leading to suboptimal overall performance. To address this issue this paper proposes a bi-level co-optimization framework that integrates deep reinforcement learning (DRL) and mixed integer programming (MIP). The outer layer employs the TD3 algorithm for capacity configuration while the inner layer uses the Gurobi solver for optimal operation under constraints. On a standalone PV–wind–load-HESS system the method attains near-optimal quality at dramatically lower runtime. Relative to GA + Gurobi and PSO + Gurobi the cost is lower by 4.67% and 1.31% while requiring only 0.52% and 0.58% of their runtime; compared with a direct Gurobi solve the cost remains comparable while runtime decreases to 0.07%. Sensitivity analysis further validates the model’s robustness under various cost parameters and renewable energy penetration levels. These results indicate that the proposed DRL–MIP cooperation achieves near-optimal solutions with orders of magnitude speedups. This study provides a new DRL–MIP paradigm for efficiently solving strongly coupled bi-level optimization problems in energy systems.

The urgent global transition toward low-carbon energy systems has highlighted the need for systematic planning of hydrogen refueling stations (HRS) to facilitate clean energy adoption. This study develops an integrated framework for regional HRS layout optimization and carbon emission assessment considering population distribution land area and hydrogen demand. Using Hainan Province as a case study the model estimates regional hydrogen demand determines optimal HRS deployment evaluates spatial coverage and refueling distances and quantifies potential carbon emission reductions under various renewable energy scenarios. Model validation with Haikou demonstrates its reliability and applicability at the regional scale. Results indicate pronounced spatial disparities in hydrogen demand and infrastructure requirements emphasizing that prioritizing station deployment in densely populated urban areas can enhance accessibility and maximize emission reduction. The framework offers a practical data-efficient tool for policymakers and planners to guide early-stage hydrogen infrastructure development and supports strategies for regional decarbonization and sustainable energy transitions.

Titanium dioxide (TiO2) is widely used in solar cells and photocatalysts given its excellent photoactivity low cost and high structural electronic and optical stability. Here a novel TiO2 composite was prepared by coating TiO2 inverse opal (IO) with TiO2 nanorods (NRs). With a porous three-dimensional network structure the composite exhibited higher light absorption; enhanced the separation of the electron–hole pairs; deepened the infiltration of the electrolyte; better transported and collected charge carriers; and greatly improved the power conversion efficiency (PCE) of the quantum-dot sensitized solar cells (QDSSCs) based on it while also boosting its own photocatalytic hydrogen generation efficiency. A very high PCE of 12.24% was achieved by QDSSCs utilizing CdS/CdSe sensitizer. Furthermore the TiO2 composite exhibited high photocatalytic activity with a H2 release rate of 1080.2 µ mol h−1 g −1 several times that of bare TiO2 IO or TiO2 NRs.

Hydrogen is widely regarded as a promising carbon-free alternative fuel. However the development of low-emission marine gas turbine combustion systems has been hindered by the associated risks of combustion instability also termed as thermoacoustic oscillations. Although there is sufficient literature on hydrogen fuel and combustion instability systematic reviews addressing the manifestations and mechanisms of these instabilities remain limited. The present study aims to provide a comprehensive review of combustion instabilities in hydrogen-enriched marine gas turbines with a particular focus on elucidating the characteristics and underlying mechanisms. The review begins with a concise overview of recent progress in understanding the fundamental combustion properties of hydrogen and then details various instability phenomena in hydrogen-enriched methane flames. The mechanisms by which hydrogen enrichment affects combustion instabilities are extensively discussed particularly in relation to the feedback loop in thermoacoustic combustion systems. The paper concludes with a summary of the key combustion instability challenges associated with hydrogen addition to methane flames and offers prospects for future research. In summary the review highlights the interaction between hydrogenenriched methane flames and thermoacoustic phenomena providing a foundation for the development of stable low-emission combustion systems in industrial marine applications incorporating hydrogen enrichment.

While community energy initiatives and pilot projects have demonstrated technical feasibility and economic benefits their site-specific nature limits transferability to systematic scalable investment models. This study addresses this gap by proposing a modular framework for Renewable Energy Valleys (REVs) developed from real-world Community Energy Lab (CEL) demonstrations in Crete Greece which is an island with pronounced seasonal demand fluctuation strong renewable potential and ongoing hydrogen valley initiatives. Four modular business schemes are defined each representing different sectoral contexts by combining a baseline of 50 residential units with one representative large consumer (hotel rural households with thermal loads municipal swimming pool or hydrogen bus). For each scheme a mixed-integer linear programming model is applied to optimally size and operate integrated solar PV wind battery (BAT) energy storage and hydrogen systems across three renewable energy penetration (REP) targets: 90% 95% and 99.9%. The framework incorporates stochastic demand modeling sector coupling and hierarchical dispatch schemes. Results highlight optimal technology configurations that minimize dependency on external sources and curtailment while enhancing reliability and sustainability under Mediterranean conditions. Results demonstrate significant variation in optimal configurations across sectors and targets with PV capacity ranging from 217 kW to 2840 kW battery storage from 624 kWh to 2822 kWh and hydrogen systems scaling from 65.2 kg to 192 kg storage capacity. The modular design of the framework enables replication beyond the specific context of Crete supporting the scalable development of Renewable Energy Valleys that can adapt to diverse sectoral mixes and regional conditions.

Algeria’s transition toward sustainable energy requires the exploitation of its abundant solar and wind resources for green hydrogen production. This study assesses the technoeconomic feasibility of an off-grid PV/wind hybrid system integrated with a hydrogen subsystem (electrolyzer fuel cell and hydrogen storage) to supply both electricity and hydrogen to decentralized sites in Algeria. Using HOMER Pro five representative Algerian regions were analyzed accounting for variations in solar irradiation wind speed and groundwater availability. A deferrable water-extraction and treatment load was incorporated to model the water requirements of the electrolyzer. In addition a comprehensive sensitivity analysis was conducted on solar irradiation wind speed and the capital costs of PV panels and wind turbines to capture the effects of renewable resource and investment cost fluctuations. The results indicate significant regional variation with the levelized cost of energy (LCOE) ranging from 0.514 to 0.868 $/kWh the levelized cost of hydrogen (LCOH) between 8.31 and 12.4 $/kg and the net present cost (NPC) between 10.28 M$ and 17.7 M$ demonstrating that all cost metrics are highly sensitive to these variations.

The article presents a comparison between the pressure conditions of a real low-pressure gas network and the results of hydraulic calculations obtained using various simulation programs and empirical equations. The calculations were performed using specialized gas network analysis software: STANET (ver 10.0.26) SimNet SSGas 7 and SONET. Additionally the simulation results were compared with calculations based on the empirical Darcy–Weisbach and Renouard equations. In the first part of the analysis two calculation models were compared. In one model the geodetic elevation of individual network nodes was included (elevation-aware model) while in the second calculations were performed without considering node elevation (flat model). For low-pressure gas networks accounting for elevation is critical due to the presence of the pressure recovery phenomenon which does not occur in medium- and high-pressure networks. Furthermore considering the growing need to increase the share of renewable energy the study also examined the network’s operating conditions when using natural gas–hydrogen mixtures. The following hydrogen concentrations were considered: 2.5% 5.0% 10.0% 20.0% and 50.0%. The results confirm the importance of incorporating elevation data in the modeling of low-pressure gas networks. This is supported by the small differences between calculated results and actual pressure measurements taken from the operating network. Moreover increasing the hydrogen content in the mixture intensifies the pressure recovery effect. The hydraulic results obtained using different computational tools were consistent and showed only minor discrepancies.

The cooling effect from the para-ortho hydrogen conversion (POC) combined with a vaporcooled shield (VCS) and multi-layer insulation (MLI) can effectively extend the storage duration of liquid hydrogen in cryogenic tanks. However there is currently no effective and straightforward empirical correlation available for predicting the catalytic POC efficiency in VCS pipelines. This study focuses on the development of correlations for the catalytic conversion of para-hydrogen to ortho-hydrogen in pipelines particularly in the context of cryogenic hydrogen storage systems. A model that incorporates the Langmuir adsorption characteristics of catalysts and introduces the concept of conversion efficiency to quantify the catalytic process’s performance is introduced. Experimental data were obtained in the temperature range of 141.9~229.9 K from a cryogenic hydrogen catalytic conversion facility where the effects of temperature pressure and flow rate on the catalytic conversion efficiency were analyzed. Based on a validation against the experimental data the proposed model offers a reliable method for predicting the cooling effects and optimizing the catalytic conversion process in VCS pipelines which may contribute to the improvement of liquid hydrogen storage systems enhancing both the efficiency and duration of storage.

During the critical period of energy transition the collaborative optimization of the electricity-hydrogentransportation coupling system is of vital importance for achieving efficient energy utilization and sustainable development.This paper proposes a collaborative operation mechanism of Distributed Robust Optimization (DRO) considering carbon emissions. Firstly a Stackelberg game dynamic pricing strategy is constructed for the integrated energy station (IES) and the electricity-hydrogen hybrid charging station (HRS) where the upper-level IES optimizes the electricity price setting strategy and the lower-level HRS dynamically adjusts the electricity purchase-hydrogen production plan. Secondly the Wasserstein distance is used to describe the uncertainties of hydrogen vehicle loads and wind-solar power generation and a bisection algorithm-column constraint generation (BA-C&CG) hybrid algorithm is designed to solve the model. Finally the numerical example verification shows that the daily operation cost of HRS under the proposed mechanism is as low as 1108.53 EUR which is 10.58 % and 7.38 % lower than that of the commonly used stochastic optimization (SO) and robust optimization (RO) respectively. The variance analysis (F = 536.05P < 0.001) confirms that the cost advantage is statistically significant. In terms of carbon emission reduction effect the DRO-Stackelberg game model has the lowest daily carbon cost (6.98EUR). This mechanism effectively balances the economic and robustness of the system and the single dispatch calculation time is only 112.09 s meeting the real-time operation requirements of engineering. It provides technical support for the low-carbon collaborative operation of the electricity-hydrogen-transportation coupling system.

A new protocol is presented to directly characterise the toughness of microstructural regions present within the weld heat-affected zone (HAZ) the most vulnerable location governing the structural integrity of hydrogen transport pipelines. Heat treatments are tailored to obtain bulk specimens that replicate predominantly ferriticbainitic bainitic and martensitic microstructures present in the HAZ. These are applied to a range of pipeline steels to investigate the role of manufacturing era (vintage versus modern) chemical composition and grade. The heat treatments successfully reproduce the hardness levels and microstructures observed in the HAZ of existing natural gas pipelines. Subsequently fracture experiments are conducted in air and pure H2 at 100 bar revealing a reduced fracture resistance and higher hydrogen embrittlement susceptibility of the HAZ microstructures with initiation toughness values as low as 32 MPa√ m. The findings emphasise the need to adequately consider the influence of microstructure and hard brittle zones within the HAZ.